ASTM_C_177_-_19.pdf

Designation:C17719Standard Test Method forSteady-State Heat Flux Measurements and ThermalTransmission Properties by Means of the Guarded-Hot-PlateApparatus1This standard is issued under the fixed designation C177;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method establishes the criteria for the labora-tory measurement of the steady-state heat flux through flat,homogeneous specimen(s)when their surfaces are in contactwith solid,parallel boundaries held at constant temperaturesusing the guarded-hot-plate apparatus.1.2 The test apparatus designed for this purpose is known asa guarded-hot-plate apparatus and is a primary(or absolute)method.This test method is comparable,but not identical,toISO 8302.1.3 This test method sets forth the general design require-ments necessary to construct and operate a satisfactoryguarded-hot-plate apparatus.It covers a wide variety of appa-ratus constructions,test conditions,and operating conditions.Detailed designs conforming to this test method are not givenbut must be developed within the constraints of the generalrequirements.Examples of analysis tools,concepts and proce-dures used in the design,construction,calibration and opera-tion of a guarded-hot-plate apparatus are given in Refs(1-41).21.4 This test method encompasses both the single-sided andthe double-sided modes of measurement.Both distributed andline source guarded heating plate designs are permitted.Theuser should consult the standard practices on the single-sidedmode of operation,Practice C1044,and on the line sourceapparatus,Practice C1043,for further details on these heaterdesigns.1.5 The guarded-hot-plate apparatus can be operated witheither vertical or horizontal heat flow.The user is cautionedhowever,since the test results from the two orientations may bedifferent if convective heat flow occurs within the specimens.1.6 Although no definitive upper limit can be given for themagnitude of specimen conductance that is measurable on aguarded-hot-plate,for practical reasons the specimen conduc-tance should be less than 16 W/(m2K).1.7 This test method is applicable to the measurement of awide variety of specimens,ranging from opaque solids toporous or transparent materials,and a wide range of environ-mental conditions including measurements conducted at ex-tremes of temperature and with various gases and pressures.1.8 Inhomogeneities normal to the heat flux direction,suchas layered structures,can be successfully evaluated using thistest method.However,testing specimens with inhomogeneitiesin the heat flux direction,such as an insulation system withthermal bridges,can yield results that are location specific andshall not be attempted with this type of apparatus.See TestMethod C1363 for guidance in testing these systems.1.9 Calculations of thermal transmission properties basedupon measurements using this method shall be performed inconformance with Practice C1045.1.10 In order to ensure the level of precision and accuracyexpected,persons applying this standard must possess aknowledge of the requirements of thermal measurements andtesting practice and of the practical application of heat transfertheory relating to thermal insulation materials and systems.Detailed operating procedures,including design schematicsand electrical drawings,should be available for each apparatusto ensure that tests are in accordance with this test method.Inaddition,automated data collecting and handling systemsconnected to the apparatus must be verified as to theiraccuracy.This can be done by calibration and inputting datasets,which have known results associated with them,intocomputer programs.1.11 It is not practical for a test method of this type toestablish details of design and construction and the proceduresto cover all contingencies that might offer difficulties to aperson without technical knowledge concerning theory of heatflow,temperature measurements and general testing practices.The user may also find it necessary,when repairing or1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Jan.1,2019.Published January 2019.Originallyapproved in 1942.Last previous edition approved in 2013 as C177 13.DOI:10.1520/C0177-19.2The boldface numbers given in parentheses refer to the list of references at theend of this standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in t